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Regulus is the brightest object in the constellation Leo, but it is not considered one of the brightest stars visible in the night sky.
Answer: False
Regulus is indeed the brightest object in the constellation Leo, and the source explicitly states it is 'recognized as one of the brightest stars visible in the night sky,' with an apparent magnitude of +1.35, making it the twenty-first brightest star.
The Bayer designation for Regulus is Alpha Leonis, which signifies its position as the second brightest star in the Leo constellation.
Answer: False
While the Bayer designation Alpha Leonis is correct, it signifies Regulus as the *brightest* star in the Leo constellation, not the second brightest. The Bayer designation typically assigns Greek letters in order of decreasing brightness.
The Regulus star system is located approximately 79 light-years from our Solar System.
Answer: True
The source explicitly states that the Regulus system is located approximately 79 light-years from our Solar System.
The traditional name 'Regulus' is derived from Greek, meaning 'great king'.
Answer: False
The traditional name 'Regulus' is derived from *Latin*, meaning 'prince' or 'little king,' not Greek for 'great king'.
The International Astronomical Union (IAU) standardized the proper name 'Regulus' in 2016.
Answer: True
The International Astronomical Union (IAU) organized a Working Group on Star Names (WGSN) in 2016, and 'Regulus' was among the first names approved and standardized.
In Chinese astronomy, Regulus is known as the First Star of Xuanyuan, the Yellow Emperor.
Answer: False
In Chinese astronomy, Regulus is known as the *Fourteenth* Star of Xuanyuan, the Yellow Emperor, not the First Star.
The Babylonians referred to Regulus as Sharru, meaning 'the King', and it marked the 15th ecliptic constellation.
Answer: True
The source confirms that the Babylonians called Regulus 'Sharru,' meaning 'the King,' and it indeed marked the 15th ecliptic constellation.
The overall apparent magnitude of the Regulus system is +8.1, with Regulus B contributing most to its brightness.
Answer: False
The overall apparent magnitude of the Regulus system is +1.35, not +8.1. Furthermore, the light output of the system is predominantly from Regulus A, not Regulus B.
Regulus is best observed in the northern hemisphere during the summer months.
Answer: False
Regulus is best observed in the northern hemisphere during late winter and spring evenings, and it is obscured by the Sun's glare during late summer (August 22-24).
The heliacal rising of Regulus, its first pre-sunrise appearance, typically occurs in late August.
Answer: False
The heliacal rising of Regulus typically occurs late in the first week of September or in the second week, not late August. Late August is when it is obscured by the Sun.
Regulus is the brightest object in which constellation?
Answer: Leo
Regulus is identified as the brightest object in the constellation Leo.
The Regulus system is approximately how many light-years from our Solar System?
Answer: 79
The Regulus system is located approximately 79 light-years from our Solar System.
The Bayer designation for Regulus is often abbreviated as Alpha Leo or α Leo. What is its full Bayer designation?
Answer: Alpha Leonis
The full Bayer designation for Regulus is Alpha Leonis.
The traditional name 'Regulus' is derived from Latin and means what?
Answer: 'Prince' or 'little king'
The traditional name 'Regulus' is derived from Latin, meaning 'prince' or 'little king'.
What does the Babylonian name 'Sharru' for Regulus mean?
Answer: The King
The Babylonians referred to Regulus as 'Sharru,' which means 'the King'.
The Arabic name 'Qalb al-Asad' for Regulus translates to what?
Answer: The Heart of the Lion
The Arabic name 'Qalb al-Asad' for Regulus translates to 'the heart of the lion'.
In Persia, Regulus was known as 'Miyan', which means what?
Answer: The Centre
In Persia, Regulus was known as 'Miyan,' meaning 'the Centre'.
The overall apparent magnitude of the Regulus system, which makes it the twenty-first brightest star, is what value?
Answer: +1.35
The Regulus system has an overall apparent magnitude of +1.35, making it the twenty-first brightest star in the night sky.
What was the purpose of the Working Group on Star Names (WGSN) organized by the IAU in 2016?
Answer: To catalog and standardize proper names for stars
The IAU's Working Group on Star Names (WGSN) was organized to catalog and standardize proper names for stars.
What is a light-year, as defined in the context of Regulus's distance?
Answer: The distance light travels in one Earth year.
A light-year is defined as the distance light travels in one Earth year.
In the northern hemisphere, Regulus is best seen in the evening during which seasons?
Answer: Late winter and spring
Regulus is best observed in the evening during the northern hemisphere's late winter and spring.
Despite appearing as a single star to the unaided eye, Regulus is actually a triple star system.
Answer: False
The source clarifies that while Regulus appears as a single star, it is actually a *quadruple* star system, composed of four stars organized into two distinct pairs.
The primary components of the spectroscopic binary Regulus A are a blue-white main-sequence star and a red dwarf.
Answer: False
The spectroscopic binary Regulus A consists of a blue-white main-sequence star and a *pre-white dwarf* companion, not a red dwarf. Red dwarfs are components of the Regulus BC pair.
The Regulus BC pair is separated from Regulus A by an angular distance of 177 arc-seconds, making them visible only with professional telescopes.
Answer: False
While the angular separation of 177 arc-seconds is correct, this distance makes the Regulus BC pair visible in *amateur* telescopes, not exclusively professional ones.
Regulus Ab, the companion to Regulus Aa, has a mass of 0.31 solar masses, consistent with its classification as a pre-white dwarf.
Answer: True
Regulus Ab has a mass of 0.31 ± 0.10 solar masses, which is indeed consistent with its classification as a pre-white dwarf.
The spectroscopic binary Regulus A consists of a blue-white main-sequence star and what companion?
Answer: A pre-white dwarf
The spectroscopic binary Regulus A consists of a blue-white main-sequence star and a pre-white dwarf companion.
What is the temperature of Regulus Ab?
Answer: 20,000 Kelvin
Regulus Ab has a temperature of 20,000 ± 4,000 Kelvin.
What is the radius of Regulus Ab?
Answer: 0.061 solar radii
Regulus Ab has a radius of 0.061 ± 0.011 solar radii.
Regulus A is classified as a blue straggler, indicating it is hotter and bluer than other stars in its cluster that formed at the same time.
Answer: True
The source defines a blue straggler as a star that appears hotter and bluer than other co-formed stars in its cluster, which is consistent with the classification of Regulus A.
The spectral type of Regulus A is M4 V, indicating it is a red dwarf.
Answer: False
The spectral type of Regulus A is B8 IVn, not M4 V. M4 V is the spectral type for Regulus C, which is a red dwarf.
Regulus A has positive U-B and B-V color indices, indicating a cooler temperature.
Answer: False
Regulus A has negative U-B (-0.36) and B-V (-0.11) color indices, which are characteristic of hotter stars. Positive values are associated with cooler temperatures, as seen in Regulus BC.
Regulus A is a confirmed variable star, with its brightness known to fluctuate significantly.
Answer: False
Regulus A is *suspected* to be a variable star, but it is not stated to be a *confirmed* variable star with significantly fluctuating brightness.
Regulus A has an equatorial radius larger than its polar radius due to its rapid rotation.
Answer: True
Regulus A's equatorial radius (4.21 solar radii) is indeed larger than its polar radius (3.22 solar radii), a direct consequence of its rapid rotation causing an oblate shape.
Gravity darkening causes Regulus A's equatorial region to be hotter and brighter per unit surface area than its poles.
Answer: False
Gravity darkening causes the *poles* of Regulus A to be considerably hotter and five times brighter per unit surface area than its equatorial region, not the other way around.
Regulus A emits polarized light because its rapid rotation causes it to have a highly oblate shape.
Answer: True
The source confirms that Regulus A emits polarized light due to its extremely rapid rotation, which results in a highly oblate (flattened) shape.
What is the evolutionary stage of Regulus A?
Answer: Blue straggler
Regulus A is classified as a blue straggler.
What is the spectral type of Regulus A?
Answer: B8 IVn
The spectral type of Regulus A is B8 IVn.
What is the equatorial radius of Regulus A?
Answer: 4.21 solar radii
Regulus A has an equatorial radius of 4.21 solar radii.
What is the surface gravity (log g) of Regulus A?
Answer: 3.54 cgs
The surface gravity (log g) of Regulus A is 3.54 ± 0.09 cgs.
What is the rotation period of Regulus A's primary star?
Answer: 15.9 hours
The primary star of Regulus A has a rotation period of only 15.9 hours.
The phenomenon where Regulus A's poles are hotter and brighter per unit surface area than its equatorial region is known as what?
Answer: Gravity darkening
The phenomenon where Regulus A's poles are hotter and brighter per unit surface area than its equatorial region is known as gravity darkening.
What is the equatorial temperature of Regulus A?
Answer: 11,010 Kelvin
Regulus A has an equatorial temperature of 11,010 Kelvin.
What is the metallicity [Fe/H] of Regulus A?
Answer: +0.21 dex
The metallicity [Fe/H] of Regulus A is +0.21 dex.
Regulus C, the faintest directly observed star in the system, has an apparent magnitude of +13.5 and requires a substantial telescope to be seen.
Answer: True
Regulus C has an apparent magnitude of +13.5, making it the faintest directly observed star in the system and necessitating a substantial telescope for its observation.
The Regulus BC pair is in the main sequence evolutionary stage, actively fusing hydrogen into helium.
Answer: True
The source confirms that the Regulus BC pair is in the main sequence evolutionary stage, which is characterized by actively fusing hydrogen into helium in their cores.
Regulus B is classified as a K2 V orange dwarf, while Regulus C is an M4 V red dwarf.
Answer: True
The source explicitly states that Regulus B has a spectral type of K2 V (orange dwarf) and Regulus C has a spectral type of M4 V (red dwarf).
What is the apparent magnitude of Regulus B, which allows it to be seen with binoculars?
Answer: +8.1
Regulus B has an apparent magnitude of +8.1, making it visible with binoculars.
Regulus B and Regulus C are classified with which spectral types, respectively?
Answer: K2 V and M4 V
Regulus B has a spectral type of K2 V, and Regulus C has a spectral type of M4 V.
What is the luminosity of Regulus B?
Answer: 0.322 solar luminosities
Regulus B has a luminosity of 0.322 ± 0.005 solar luminosities.
What is the temperature of Regulus B?
Answer: 4,968 Kelvin
Regulus B has a temperature of 4,968 Kelvin.
What is the metallicity [Fe/H] of Regulus B?
Answer: -0.21 dex
The metallicity [Fe/H] of Regulus B is -0.21 dex.
The radial velocity of Regulus A is 4.39 ± 0.09 kilometers per second, indicating it is moving away from the observer.
Answer: True
The radial velocity of Regulus A is indeed 4.39 ± 0.09 kilometers per second. A positive radial velocity value indicates that the star is moving away from the observer.
Regulus A exhibits a proper motion of -248.73 milliarcseconds per year in Right Ascension and 5.59 milliarcseconds per year in Declination.
Answer: True
The source provides the proper motion values for Regulus A as -248.73 ± 0.35 milliarcseconds per year in Right Ascension and 5.59 ± 0.21 milliarcseconds per year in Declination.
Regulus A has an absolute magnitude of -0.57, which is a measure of its intrinsic brightness.
Answer: True
Regulus A has an absolute magnitude of -0.57, and absolute magnitude is indeed a measure of a star's intrinsic brightness, standardized to a distance of 10 parsecs.
The orbital period of Regulus Aa and Ab is approximately 40.102 days, indicating a very wide binary system.
Answer: False
The orbital period of 40.102 days is correct, but this relatively short period indicates a *close* binary system, not a very wide one.
The eccentricity of the orbit for Regulus Aa and Ab is assumed to be 1, indicating a highly elongated orbit.
Answer: False
The eccentricity of the orbit for Regulus Aa and Ab is assumed to be 0, indicating a *perfectly circular* orbit, not 1, which would imply a parabolic or highly elongated orbit.
Regulus A's proper motion in Right Ascension is approximately what value?
Answer: -248.73 milliarcseconds per year
Regulus A exhibits a proper motion of -248.73 ± 0.35 milliarcseconds per year in Right Ascension.
Regulus A has an absolute magnitude of what value?
Answer: -0.57
Regulus A has an absolute magnitude of -0.57.
What is the approximate orbital period of Regulus Aa and Ab?
Answer: 40.102 days
The orbital period of Regulus Aa and Ab is approximately 40.102 days.
What is the assumed eccentricity of the orbit for Regulus Aa and Ab?
Answer: 0 (perfectly circular)
The eccentricity of the orbit for Regulus Aa and Ab is assumed to be 0, indicating a perfectly circular orbit.
What is the semi-major axis of the orbit for Regulus Aa and Ab?
Answer: 74 solar radii
The semi-major axis of the orbit for Regulus Aa and Ab is 74 solar radii.
Regulus is located 0.465 degrees from the ecliptic, making it the closest bright star to this plane.
Answer: True
The source explicitly states that Regulus is located 0.465 degrees from the ecliptic, making it the closest bright star to this plane.
Lunar occultations of Regulus occur annually due to its close proximity to the ecliptic.
Answer: False
While Regulus's proximity to the ecliptic does cause frequent lunar occultations, they occur in 'spates' approximately every 9.3 years, not annually.
The last planetary occultation of Regulus was by Mars in 1959.
Answer: False
The last planetary occultation of Regulus occurred on July 7, 1959, but it was by *Venus*, not Mars.
During the 2005 occultation of Regulus by asteroid 166 Rhodope, measurements of differential light bending were consistent with predictions of general relativity.
Answer: True
The source confirms that during the 2005 occultation by asteroid 166 Rhodope, measurements of differential light bending were indeed consistent with the predictions of general relativity.
What is the precise angular distance of Regulus from the ecliptic, making it the closest bright star to this plane?
Answer: 0.465 degrees
Regulus is located 0.465 degrees from the ecliptic, making it the closest bright star to this plane.
Lunar occultations of Regulus occur in spates approximately every how many years?
Answer: 9.3 years
Lunar occultations of Regulus occur in spates approximately every 9.3 years.
The next predicted planetary occultation of Regulus is by Venus on what date?
Answer: October 1, 2044
The next predicted planetary occultation of Regulus will be by Venus on October 1, 2044.
The 2005 occultation of Regulus by asteroid 166 Rhodope provided measurements consistent with general relativity regarding what phenomenon?
Answer: Differential bending of light.
The 2005 occultation of Regulus by asteroid 166 Rhodope provided measurements of differential light bending that were consistent with general relativity.
The initial age estimate for Regulus A was around 1 billion years, but the white dwarf companion suggested it was much younger.
Answer: False
The initial age estimate for Regulus A was 50-100 million years. It was the presence of the white dwarf companion that suggested the system was *at least 1 billion years old*, implying it was much *older* than initially thought.
The brown dwarf SDSS J1007+1930 is definitively gravitationally bound to the Regulus system due to its close proximity.
Answer: False
The gravitational binding of SDSS J1007+1930 to Regulus is considered *uncertain* due to its extreme distance from the system, not definitive due to close proximity.
SDSS J1007+1930 is estimated to have a mass of roughly 60 Jupiter masses and a spectral type of L9 or T0.
Answer: True
The brown dwarf SDSS J1007+1930 is estimated to have a mass of roughly 60 Jupiter masses (0.06 solar masses) and a spectral type of L9 or T0.
The gravitational binding of SDSS J1007+1930 to Regulus is considered uncertain primarily because its metal abundance is significantly different from Regulus B.
Answer: False
The gravitational binding of SDSS J1007+1930 to Regulus is uncertain primarily due to its *extreme distance* from the system. The source actually suggests its metal abundance is *similar* to Regulus B, which supports a potential binding, not disproves it.
What is the minimum estimated age of the Regulus system, as indicated by its white dwarf companion?
Answer: 1 billion years
The presence of a white dwarf companion suggests the Regulus system is at least 1 billion years old, as this is the minimum time required for a white dwarf to form.
What is the estimated mass of the brown dwarf SDSS J1007+1930?
Answer: 0.06 solar masses
SDSS J1007+1930 is estimated to have a mass of roughly 0.06 solar masses (60 Jupiter masses).
SDSS J1007+1930 is classified with which spectral type?
Answer: L9 or T0
SDSS J1007+1930 has a spectral type of L9 or T0.